Description of ResearchThe research in my laboratory is conducted in collaboration with Dr. Gary H. Cohen of the School of Dental Medicine, UPenn. Our longterm goal is to understand molecular events that mediate virus entry into susceptible cells and promote the pathogenesis of the virus in its human host.

Research on herpes simplex virus (HSV): Four viral glycoproteins, gB, gD, gH and gL are essential for virus entry and spread. HSV entry is mediated by one of several different receptors. including HVEM (HveA) a TNF receptor, and nectin-1, a cell adhesion molecule that is a member of the Ig superfamily. We showed that purified gD interacts directly with purified HVEM and nectin-1 using such techniques as co-precipitation, ELISA and biosensor. In collaboration with two crystallographers, Andrea Carfi, now at Novartis and Ekaterina Heldwein, now at Tufts University, we have solved the structures of all of the “players” in HSV entry, including gD bound to HVEM, gD bound to nectin-1, gB and gH/gL. These structures, in conjunction with our ongoing efforts to understand the relationship between structure and function have led us to propose that HSV entry follows a pathway that begins with binding of gD to one of its two receptors. This interaction leads to a conformational change to gD that activates it so that it signals to gH/gL, the regulator of fusion, which is then carried out by gB. Of particular interest is the fact that both gH/gL and gB are highly conserved among all herpesviruses, including the plethora of animal herpesviruses that cause serious diseases of both companion animals and farm and zoo animals. Thus our work has direct relevance to veterinary medicine. It also has relevance to human medicine as there are at least eight human herpesviruses, several of which cause serious diseases such as chicken pox, shingles, lymphomas to name just a few. Our work continues to focus on the mechanisms that regulate the entry pathway.

Poxvirus Research: Another aspect of our work is to focus on poxviruses such as variola (smallpox) and vaccinia (the virus used as a vaccine against smallpox). We are using similar techniques to those above to study the envelope proteins of vaccinia virus (VV). Our two goals are to understand the very complex entry process as well as to develop subunit vaccines that could be used to augment the live virus anti-smallpox vaccine currently used for vaccinating members of the armed forces. This vaccine, though it has been effective enough to eradicate smallpox worldwide is not without serious side effects and cannot be used in immunocompromised or pregnant individuals. Currently, we are focusing on a key entry protein, L1 , for which we have evidence is the receptor binding protein for vaccinia. We have proposed a novel model for how L1 works. This is called the myristoyl switch model, a way that L1 undergoes a conformational change that triggers the entry-fusion complex to carry out fusion.

A very similar protein is present in most orthopox virusesThe proteins and antibodies we have developed have been evaluated alone and in combination as protective reagents in both mouse and monkey modelsstudent will use the materials at hand to master the technique and apply it to new questions concerning virus entry, receptor down regulation and events that focus on glycoproteins during viral replication.